1. Field of the Invention
The invention relates to an economical and easy to install geothermal heat-pump system which utilizes horizontal ground loops. The system is environmentally friendly and can be installed in most already developed locations, such as existing apartment complexes, as well as to-be-developed areas. The invention is directed to novel heat exchange loops, the method of installing the loops and devices for use in the installation process and in association with the loops.
2. Description of the Related Art
The instant invention involves the use of the earth as a constant source of heat to be extracted by a heat pump. Geothermal or ground-source heat pumps, although costly to install, have been found to more efficiently heat and air condition building spaces than other heat pumps. It is much more efficient to extract heat from a substance such as earth, which has a near-constant temperature, than from air which can be subject to severe temperature variations.
Prior art geothermal systems have utilized ground loops that have been installed horizontally using open trenches. Horizontal installation, however, causes significant damage to the environment. Nature has suffered from root-system damage and removal of vegetation caused by the huge displacement of earth required by horizontal ground loop installation. Landscaping has often been destroyed by the large displacement of earth, removal of trees, shrubs, structures, and grass. Parking lots, driveways, sidewalks, and curbs have been removed, damaged, or their installation delayed for long periods of time to allow for the settling that must occur after massive displacements of earth. Moreover, polluted run-off from the large excavations has disturbed the environmental in areas beyond the job site. Furthermore, the hunge excavating equipment is destructive in its weight, size, and polluting use of fossil fuels.
The installation of prior horizontal ground loops requires the subcontracting of big, expensive equipment and specialized personnel to perform very time-consuming drilling, excavating of treaches, and installation. The equipment used for these excavations is extremely expensive and is not owned by many HVAC installers. The man-hours required to install prior art horizontal loops is extensive and costly. Deep, dangerous ditches are dug and painstakingly prepared. Workers then spend many hours installing specialized pipes and fittings. Finally, the ditches are carefully filled and left for settling. Land that has had a prior art ground loop system installed must remain untouched for as much as a year and a quarter to allow for settling. This is an unacceptable delay to the installation of landscaping, parking lots, sidewalks, curbs, driveways, etc. The untouched ground is not only unsightly, but provides dust which is carried by the wind to undesirable places (i.e. indoor surfaces, wet paint and caulk, lungs, eyes, etc.).
Many owners of modern homes and commercial buildings, as well as town houses, condominiums, apartments, etc, have land areas that are too restrictive for prior art horizontal ground loop installation. Many homeowners wishing to change to geothermal heating systems forego the conversion due to the destruction or existing landscaping and wooded areas as well as other improvements. The ditch excavation required for prior art ground loops is simply not feasible for homes located on rocky land.
The obvious next step is to install vertical ground loops. Vertical ground loop installation requires the use of large cumbersome 6" vertical boring machinery mounted on large trucks weighing in at 15 tons or more. Few people want these monstrous machines in their yards to destroy their driveways and landscaping. These machines are noisy, leave large piles of cuttings and muddy streams of run-off water. The vibrations caused by the machinery can crack foundations and basement walls when drilling near buildings. The depth of vertical bore-holes can penetrate subterranean caverns and the water aquifer. State water control boards have expressed a preference for horizontal instead of vertical ground loops because of the greater threat to drinking water contamination posed by the vertical loop installation. Furthermore, in the case of cavern penetration, well inspectors will require cement trucks to fill a large cavern. Cement is much too expensive to waste on cavern filling. The earth's crust is full of caverns and underground rivers, creating money pits for vertical ground-loop installers.
As with horizontal ground loops, the cost of vertical ground loops is prohibitive. Drilling or trenching equipment is not typically owned by HVAC professionals because it is unique and costs thousands to hundreds of thousands of dollars for one machine. The cost of casing, pipe, fittings, cement, bits, and drill stems required for vertical ground loops can be high. Substantial expense is further incurred in the man-hours required to install the vertical loop system in the bore-holes before they cave-in. During rainy seasons, a sea of mud can fill bore-holes the minute the drill bit is pulled, rendering the bore-holes useless. The large, 6" bore-holes must also be filled with some substance to facilitate the conduction of heat between bore-hole walls and the heat transfer medium-carrying pipe. This substance is a costly one not needed in the instant invention.
Although vertical ground loops have been put in places where prior art horizontal loops have not been feasible, the small yards of many homes have still been off limits to huge drilling equipment. Thus, because of destruction to landscaping and size and weight of water well construction drill rigs, in some rocky soil, vertical ground loops have not been feasible or desired in many cases.
Additionally, vertical ground loops have suffered from design problems, i.e. poor flow distribution, velocity problems are liquid or oil accumulating in the bottom of the vertical ground loops. Moreover, a simple, inexpensive way of preventing flash gas from occurring when supply and return conduits are in the same bore-hole has heretofore been unobtainable.
Also of paramount importance is the superiority of direct-exchange (DX) geothermal heat pump systems over indirect-exchange systems. In indirect-exchange systems (water-source), additional pumps to circulate a liquid other than the refrigerant in an additional indoor heat exchanger results in greater pump horse power being required. An additional heat exchanger is required because the transfer of heat goes from ground to ground-loop liquid (water) to refrigerant to air. In DX systems, however, the heat goes from ground to refrigerant to air, thus eliminating not only a heat exchanger and various pumps, but also the bothersome water and anti-freeze mixture in the ground-loop. Furthermore, the plastic pipe used in prior art water-source ground-loops has been large, cumbersome, crinkled easily, and provided too much resistance when being inserted into bore-holes.